Proper ceiling vapor barrier. Vapor barrier of wooden ceiling

The ceiling is a complex multi-layer construction. Beautiful finishes - not an indicator of quality and functionality. To maintain optimum humidity in the room, to prevent the occurrence of mold and mildew, proper vapor barrier of the ceiling must be performed. To avoid mistakes at work will help the study of all aspects and adherence to technology laying material.

ceiling vapor barrier

Why do I need a ceiling vapor barrier?

Every room has its own microclimate. Depending on the season and weather, temperature and humidity change periodically. During the heating season, warm air is mixed with cold and, converting to steam, rises. Constant exposure to moisture has a detrimental effect on the ceiling, over time the structure will collapse and rot, mold will start to appear, which is very detrimental to human health.The vapor barrier of the ceiling serves as a kind of barrier against the ingress of steam into the ceiling. It helps to form the right microclimate of the room.


The ceiling vapor barrier is at first glance an inconspicuous procedure on the scale of the whole house, but it is she who will preserve the desired atmosphere and the integrity of the building for many years.

proper ceiling vapor barrier

Main advantages:

  • The service life of the truss system and floors is much longer.
  • The appearance of mold and fungi is excluded.
  • Room heat loss is minimal.
  • Fire safety increases.
  • Paroizolyatsionny materials do not demand service throughout all term of operation.

Materials for vapor barrier

In modern construction, the vapor barrier of the house ceiling allows the use of quite diverse materials, but not all of them perform their functions equally well. Therefore, you should carefully consider the choice. It is necessary to take into account not only the material, but also the design features of the roof.

The ceiling vapor barrier in a wooden house allows the use of only special materials. Condensate accumulates on the surface of a simple film; its structure does not provide moisture release.Specialized materials have a porous structure that provides optimum moisture.

Specialized paroizolyatsionny polypropylene film

vapor barrier home ceiling

The main advantage of this material is high strength, resistance to high temperatures and light. During the construction of the roof such a film is able to protect the house from snow, rain and other natural influences. When working with similar materials, many have difficulties when the ceiling is directly vapor-proofed. Which side to lay the film? This is a basic question for beginners. Polypropylene film is one-sided and is laid with a rough side down and glossy up. When vapor barrier ceilings in the design should be provided for the ventilation gap. Currently, such material is often used. High vapor permeability and reasonable price make it very popular.

Under-roof nonwovens

This type of vapor barrier is reinforced with a cloth or special mesh, which gives additional strength. Roofing vapor barrier materials can be of different types.

ceiling vapor barrier which side

Non-perforated films are better suited for insulation work. However, their vapor permeability is much lower than that of polypropylene woven analogues. There are also options with a reflective layer. They are more suitable not for residential premises, but for use in baths, pools or bathrooms.

Breathing membrane

Have excellent steam pass characteristics. Made of synthetic material with a special structure. Vapor barrier of a wooden ceiling using a breathable membrane will provide high condensation of the room. Recently a new type of such material has appeared. The capacity depends on the humidity and the temperature in the room.

Steam insulation in the bath

If the ceiling in a residential building can do without vapor barrier, then this stage is necessary in the bath. Hot fumes are concentrated primarily at the top of the room, their penetration into the ceiling is unacceptable.

vapor barrier wooden ceiling

The ceiling vapor barrier in the bath is made by quite different methods: from old, proven to innovative, using modern materials:

  1. The log ceiling is sheathed with a board or lath with a minimum thickness of 6 cm.Impregnated (waxed) paper or aluminum foil is used as a vapor barrier material. After installation of the selected material, the entire perimeter of the ceiling is covered with a layer of clay, and the insulation is placed on top.
  2. Another method involves the use of uncircumcised boards. The beams of the ceiling are sheathed with a board, after which the vapor barrier material is laid, covered with clay and insulation. After that, the clapboard cladding is installed. For the decoration of baths most often use wooden paneling of linden or aspen.
  3. In modern construction, outdated materials and clay are often not used, they are replaced by newer vapor barrier materials. In the vapor barrier baths use membranes based on foil, bitumen or polyethylene. The technology of laying is the same as in other structures, the only feature is the laying of a thick layer of insulation and the subsequent finishing of wood.

Styling tips

steam ceiling ceiling in the bath

Before laying the vapor barrier on the ceiling, you need to make sure that there is a heater or create a rough design, inside of which the heat-shielding material is placed.It is necessary for the proper functioning of the entire ceiling system.

For proper protection of thermal insulation materials, ceiling vapor barrier must be performed in accordance with the following rules:

  • Before installation, all parts of the roof (chimney, ventilation, duct) should be sealed. This is to prevent the ingress of moisture from the outside.
  • The vapor barrier layer is laid between the insulation and the room.
  • Most materials are mounted in the same way. For mounting to wooden structures apply nails with a large cap or staple, hammered with a stapler. When mounted on concrete or metal, special adhesive tapes are used.
  • If the vapor barrier film has a reflective foil layer, this layer must be placed inside the room. Between the insulation and the film should leave a distance for ventilation.
  • The film should cover the entire perimeter of the ceiling without gaps and breaks. At the joints should be left overlap (minimum 10 cm). Rows of vapor barrier material are fastened with construction tape or reinforced with slats.
  • The fixed membrane should be moderately stretched, without sagging.

The ceiling vapor barrier is a rather complicated process. When starting work, you need to learn all the subtleties and technology of installation, or use the services of qualified professionals.

Steam Insulation Step-by-Step Guide

how to lay a vapor barrier on the ceiling

Like the roof, the ceiling of a wooden house has a multilayer structure. Each layer performs its function:

  • The top layer is the floor of the attic. It protects the entire ceiling structure from the penetration of dirt and dust. Also, the floor of the attic space makes it possible to move around without damaging the heat-insulating materials of the ceiling.
  • The attic floor is laid across the beams, on the bars. These bars press the first layer of the vapor barrier membrane. The result is a gap between it and the floor.
  • Between the ceiling beams fit insulating material. Mineral wool or foam plastic can play its role. Rock wool absorbs moisture, but its advantage is fire safety. The properties of the foam are completely opposite: it does not absorb moisture, but it is highly flammable.
  • The draft ceiling is attached to the beams from the side of the room.It is a framework for final finishing, a vapor barrier is attached to it.
  • If the final finish will be done with drywall, the vapor barrier is attached to the rough ceiling with bars or slats.
  • The final finish can be carried out using any materials: lining, battens, drywall or wood-based panels.

Methods for final finishing of a paroisolated ceiling of a wooden house

There are several ways to finish the ceiling:

  • With the help of wooden wall paneling or siding.
  • Suspended plasterboard system.
  • Finished polished timber.
  • Shelf ceiling.

For the installation of a perfectly flat hem ceiling, OSB sheets, plywood or similar sheet material are used. They are firmly fixed on the structure butt to each other. Fasteners are chosen depending on the weight of the material, mainly screws. All communications are carried out before the final finish. When mounting the suspension system equip additional fasteners.

After examining all the above features and stages of work, you can make a vapor barrier on your own in a wooden house. When buying a material, in order to avoid unnecessary costs, you need to measure the quadrature and, based on this, purchase the right amount.Proper vapor barrier is the key to a healthy atmosphere in the house.

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